public abstract class SimpleExpression extends Expression implements Callable
An implementation of this class must supply the Callable.call(XPathContext, net.sf.saxon.om.Sequence[])
method to evaluate the expression and return its result.
| Modifier and Type | Field and Description |
|---|---|
protected Expression[] |
arguments |
static Expression[] |
NO_ARGUMENTS |
EFFECTIVE_BOOLEAN_VALUE, EVALUATE_METHOD, EVENT_FEED_METHOD, INHERITED_CONTEXT, INSPECTION_CONTEXT, ITEM_FEED_METHOD, ITERATE_METHOD, locationId, MAX_SEQUENCE_LENGTH, MAX_STRING_LENGTH, NAVIGATION_CONTEXT, NODE_VALUE_CONTEXT, PROCESS_METHOD, PUSH_SELECTION, staticProperties, UNBOUNDED_LOWER, UNBOUNDED_UPPER, W3C_CONSUMING, W3C_FREE_RANGING, W3C_GROUP_CONSUMING, W3C_MOTIONLESS, WATCH_METHOD| Constructor and Description |
|---|
SimpleExpression()
Constructor
|
| Modifier and Type | Method and Description |
|---|---|
int |
computeCardinality()
Determine the static cardinality of the expression.
|
int |
computeDependencies()
Compute the dependencies of an expression, as the union of the
dependencies of its subexpressions.
|
Expression |
copy()
Copy an expression.
|
Item |
evaluateItem(XPathContext context)
Evaluate an expression as a single item.
|
void |
explain(ExpressionPresenter destination)
Diagnostic print of expression structure.
|
Expression[] |
getArguments()
Get the subexpressions (arguments to this expression)
|
String |
getExpressionType()
Return a distinguishing name for the expression, for use in diagnostics.
|
ItemType |
getItemType(TypeHierarchy th)
Determine the data type of the items returned by this expression.
|
SequenceIterator<? extends Item> |
iterate(XPathContext context)
Return an Iterator to iterate over the values of a sequence.
|
Iterator<Expression> |
iterateSubExpressions()
Get the immediate sub-expressions of this expression.
|
Expression |
optimize(ExpressionVisitor visitor,
ExpressionVisitor.ContextItemType contextItemType)
Perform optimisation of an expression and its subexpressions.
|
void |
process(XPathContext context)
Process the instruction, without returning any tail calls
|
Expression |
promote(PromotionOffer offer,
Expression parent)
Offer promotion for this subexpression.
|
boolean |
replaceSubExpression(Expression original,
Expression replacement)
Replace one subexpression by a replacement subexpression
|
void |
setArguments(Expression[] sub)
Set the immediate sub-expressions of this expression.
|
Expression |
simplify(ExpressionVisitor visitor)
Simplify the expression
|
Expression |
typeCheck(ExpressionVisitor visitor,
ExpressionVisitor.ContextItemType contextItemType)
Perform type checking of an expression and its subexpressions.
|
addToPathMap, adoptChildExpression, checkForUpdatingSubexpressions, checkPermittedContents, computeSpecialProperties, computeStaticProperties, doPromotion, dynamicError, effectiveBooleanValue, evaluateAsString, evaluatePendingUpdates, explain, getCardinality, getColumnNumber, getColumnNumber, getConstructType, getContainer, getDependencies, getEvaluationMethod, getExecutable, getExpressionCompiler, getExpressionName, getHostLanguage, getImplementationMethod, getIntegerBounds, getIntrinsicDependencies, getLineNumber, getLineNumber, getLocationId, getLocationProvider, getObjectName, getProperties, getProperty, getPublicId, getSlotsUsed, getSpecialProperties, getStreamability, getStreamingAdjunct, getSystemId, getSystemId, hasVariableBinding, implementsStaticTypeCheck, isSubtreeExpression, isUpdatingExpression, isVacuousExpression, iterateEvents, iterateSubExpressionInfo, markTailFunctionCalls, resetLocalStaticProperties, setContainer, setEvaluationMethod, setFiltered, setFlattened, setLocationId, staticTypeCheck, suppressValidation, toPattern, toStreamingPattern, toString, typeErrorpublic static final Expression[] NO_ARGUMENTS
protected Expression[] arguments
public void setArguments(Expression[] sub)
sub - an array containing the sub-expressions of this expressionpublic Iterator<Expression> iterateSubExpressions()
iterateSubExpressions in class Expressionpublic boolean replaceSubExpression(Expression original, Expression replacement)
replaceSubExpression in class Expressionoriginal - the original subexpressionreplacement - the replacement subexpressionpublic Expression simplify(ExpressionVisitor visitor) throws XPathException
simplify in class Expressionvisitor - an expression visitorXPathException - if an error is discovered during expression
rewritingpublic Expression typeCheck(ExpressionVisitor visitor, ExpressionVisitor.ContextItemType contextItemType) throws XPathException
ExpressionThis checks statically that the operands of the expression have the correct type; if necessary it generates code to do run-time type checking or type conversion. A static type error is reported only if execution cannot possibly succeed, that is, if a run-time type error is inevitable. The call may return a modified form of the expression.
This method is called after all references to functions and variables have been resolved to the declaration of the function or variable. However, the types of such functions and variables may not be accurately known if they have not been explicitly declared.
If the implementation returns a value other than "this", then it is required to ensure that the location information in the returned expression have been set up correctly. It should not rely on the caller to do this, although for historical reasons many callers do so.
typeCheck in class Expressionvisitor - an expression visitorcontextItemType - the static type of "." at the point where this expression is invoked.
The parameter is set to null if it is known statically that the context item will be undefined.
If the type of the context item is not known statically, the argument is set to
Type.ITEM_TYPEXPathException - if an error is discovered during this phase
(typically a type error)public Expression optimize(ExpressionVisitor visitor, ExpressionVisitor.ContextItemType contextItemType) throws XPathException
ExpressionThis method is called after all references to functions and variables have been resolved to the declaration of the function or variable, and after all type checking has been done.
optimize in class Expressionvisitor - an expression visitorcontextItemType - the static type of "." at the point where this expression is invoked.
The parameter is set to null if it is known statically that the context item will be undefined.
If the type of the context item is not known statically, the argument is set to
Type.ITEM_TYPEXPathException - if an error is discovered during this phase
(typically a type error)public Expression copy()
copy in class Expressionpublic Expression promote(PromotionOffer offer, Expression parent) throws XPathException
promote in class Expressionoffer - details of the offer, for example the offer to move
expressions that don't depend on the context to an outer level in
the containing expressionparent - the parent of this expressionXPathException - if any error is detectedpublic ItemType getItemType(TypeHierarchy th)
getItemType in class Expressionth - the type hierarchy cachepublic int computeCardinality()
computeCardinality in class ExpressionStaticProperty.ALLOWS_ZERO_OR_ONE,
StaticProperty.EXACTLY_ONE, StaticProperty.ALLOWS_ONE_OR_MORE,
StaticProperty.ALLOWS_ZERO_OR_MOREpublic int computeDependencies()
computeDependencies in class Expressionpublic final Item evaluateItem(XPathContext context) throws XPathException
evaluateItem in class Expressioncontext - The context in which the expression is to be evaluatedXPathException - if any dynamic error occurs evaluating the
expressionpublic final SequenceIterator<? extends Item> iterate(XPathContext context) throws XPathException
iterate in class Expressioncontext - supplies the context for evaluationXPathException - if any dynamic error occurs evaluating the
expressionpublic final void process(XPathContext context) throws XPathException
process in class Expressioncontext - The dynamic context, giving access to the current node,
the current variables, etc.XPathException - if a dynamic error occurspublic Expression[] getArguments()
public void explain(ExpressionPresenter destination)
explain in class Expressiondestination - the expression presenter used to display the structurepublic String getExpressionType()
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